Wireless transmission system



March 29, 1927. 1,622,654

D. G. LITTLE WIRELESS TRANSMISSION SYSTEM Filed July 20. 1922 To (Source jof Radio Freqflanay Oscillanorw INVENTOR Donald G. Little ATTZORINEY WITNESSES:

Patented Mar. 29, 1927.

PQNAPD LI a en Application filed July 20, 1922.

My invention relates to wireless telegraphy systems, *hav ing particular relation to. wireless transn ns sion systems.

Inits broad aspect', anobgect of my invention is to provide an electnical'systemscoms prising a pair of seriesconnected capacitive reac tors'and a high iinpedance conductive leakage path which is shunted around one of said reactors for decreasing the accumulation' of an electrical charge on the other of said capacitive reactors.

More specifically, an object of my invention is to provide means for preventing the accumulation of heavy static charges on the antennae of wireless transmission systems.

In the operation of large wireless transmitting stations it has been found that improved results are obtained by constructing the aerial system of relatively large dimensions such that the natural wave-length thereof is greater than the desired operating wave-length and then employing a tuning condenser to decrease the natural wavelength of the aerial system to approximately the desired value.

In carrying such arrangement into practice, considerable difiicult-y has been experienced because of the tendency for the antenna to accumulate large static charges which would finally puncture the tuning condenser or cause a flash-over around the edges thereof. When a flash-over or rupture occurred the transmission system would obviously be rendered inoperative.

The foregoing difliculties may be overcome in my invention by shunting the tuning condenser with a leakage path having a high impedance to currents of the transmitter frequency, all as described more fully hereinafter.

lVith these and other objects and application in view, my invention further consists in the circuit arrangement and in the details of construction. and operation. hereinafter described and claimed and illustrated in the accompanying drawing, wherein the single figure is a diagrammatic view of circuits and apparatus embodying my invention.

For purposes of illustration, my invention is shown as applied to a particular aerial system, but it is to be expressly understood that my invention is not necessarily limited thereto. The particular aerial system mentioned comprises a relatively high antenna am}, or wI Km'sBiinGf PENNSYLYAEIA, ssrenon TO wEsriNG-- LWIRE LESS TRANSMISSION SYSTEM.

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1, a relatively low antenna .or counter-force 2 and a conductor 3-for interconnecting the same. A tuning inductive reactor-t'which is included in the conductor 3-may be operatively associated with a source of radiofrequency oscillations (not shown) through a? coupling coil 5., Theaerial system may be connected to ground by means of a ground conductor 6 which extends from an adjustable tap point 7 on the tuning reactor 4:. The position of the tap point 7 is such as to cause the most efficient operation of the aerial system,that is, the greatest radiation, and may be determined by trial.

As hereinbefore stated, it has been found that improved operation is effected by employing an aerial system of relatively large dimensions which has a natural wave-length in excess of the desired operating wavelength and then decreasing the natural wavelength of the system by means of a capacitive reactance device. As shown in the drawing, this is accomplished 'by including a condenser 8 in series circuit relation with a portion of the conductor 3 between the antenna 1 and the tuning coil 4, the condenser having such value as to efiectthe desired decrease in wave-length.

With the condenser 8 connected in the position stated, the antenna 1 is insulated from ground for charges which accumulate thereon. I have found that by shunting the condenser 8 with a high-impedance leakage path 9 the charges, which tend to accumulate on the antenna 1, readily pass to ground without rendering the antenna system inoperative. The impedance of the leakage path 9 is preferably supplied by a high-impedance resistor 10 because the impedance thereof is substantially independent of frequency. In view of thefact that the resistance of the present type of high-impedance resistors decreases with time owing to the deteriorating effect of radio-frequency currents, a radio choke coil 11 may be included in series circuit relation with the resistor 10, as a matter of protection. In one particlar embodiment of my invention, the value of the resistor 10 is one megohm, the inductance of the choke coil 11 is ten millihenries and the antenna are each 200 feet long and spaced 115 feet apart.

In operation, when there is a tendency for a heavy static charge to become established on the antenna 1, as by reason of the passage of a statically charged cloud, the antenna charge leaks to ground through the leakage path 9, a portion of the inductor 4 and the ground conductor 5.

While I have shown a specific embodiment of my invention and While I have enumerated certain specific values in connection therewith, I do not desire my invention to be limited thereby and I desire that only such limitations shall be imposed thereon as are demanded by the prior art or as are set forth. in the following claims.

I claim as my invention:

1. In a Wireless transmission system, a pair of spaced antennae, an electrical circuit conductively associating said antennae, said circuit including a capacitive reactor and an inductive reactor, a ground connection extending from a point on said inductive reactor and a high impedance discharge path shunted around said capacitive reactor.

2. In a radio signaling system, the combination with a pair of spaced antennae, of an electrical circuit interconnecting the same, said circuit including a tuning inductive reactance device, a tuning capacitive reactance device and a leakage path shunted around said capacitive reactance device comprising a high impedance resistor and a radio-frequency choke coil.

In testimony whereof, I have hereunto subscribed my name this 17th day of July,

DONALD G. LITTLE. 

